Field of the Invention
The present invention discloses MEMS (Micro-Electromechanical Systems) self-aligning high/low comb teeth and a manufacturing method of the comb teeth, and belongs to the MEMS field.
Background Art
The MEMS (Micro-Electromechanical systems) field is a new field of manufacturing micro-devices that may integrate the effects of different physical fields. Compared with conventional mechanical devices, MEMS devices are smaller in dimensions, usually at micrometer to millimeter scale. Based on the semiconductor integrated circuit (IC) manufacturing process, MEMS devices can be produced massively at a low cost, utilizing the matured techniques and process in IC production extensively; therefore, the cost-performance of MEMS devices is greatly improved when compared with the “machinery” manufactured with the conventional manufacturing techniques.
Comb teeth structures are widely applied in MEMS devices, such as various capacitive transducers including accelerometers, gyroscopes, etc. and micro-actuators. MEMS comb teeth structures are usually flat, i.e., the movable comb teeth and the fixed comb teeth are in the same plane. Such comb teeth can only be driven to move in the plane. When out-of-plane movement is required, high/low comb teeth, which are also referred to as vertical comb teeth, must be used, i.e., the movable comb teeth and the fixed comb teeth are not in the same plane. High/low comb teeth structures can be used to manufacture scanning micro-mirrors, and are indispensable structures for tri-axial accelerometers and tri-axial MEMS capacitive gyroscopes. However, high/low comb teeth have to be formed by bonding or repeated etching in the process. The process is complex and involves high difficulties, resulting in a low yield ratio.
With the existing high/low comb teeth design, whether bonding is utilized to etch the high/low comb teeth respectively or repeated photo-etching is utilized to etch the high/low comb teeth respectively in the conventional MEMES manufacturing process, high-precision alignment is required. Consequently, the processing requirement is high, and the yield ratio is low. Though the SOI (Silicon-On-Insulator) technique can solve the problem of self-alignment of the comb teeth, it also has drawbacks such as repeated etching and complex processing.